Voltage regulation



Dec. 14, 1943. J. w, ALLEN 2,336,523

VOLTAGE REGULATION Filed Aug. 26, 1941 JOsep/Z. WA llew.

Patented Dec. 14, 1943 UNITED STATES PATENT OFFICE VOLTAGE REGULATION Joseph W. Allen, East Orange, N. J., assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application August 26, 1941, Serial No. 408,375 2 Claims. (Cl. 201- 51) This invention relates to voltage regulation, and particularly to the regulation of generator voltage by control of the resistance to current flow in a component part of the generator assembly, such as the shunt field circuit.

The use of carbon pile or equivalent pressure responsive resistors to control current strength is old in the art. It is also old to provide switch mechanism for short-circuiting such resistors, in order to eliminate entirely one or more sections of such resistance; for even after said sections have been compressed the maximum amount, there is still more or less resistance to current flow therethrough.

Such short-circuiting devices as have been suggested heretofore have not been satisfactory for, one reason or another; a principal difllculty being due to the lack of sufiicient sensitivity to slight pressure increments in either direction. Because of this lack of sufilcient sensitivity the complete elimination of all resistance would not occur with the degree of promptness necessary to secure good regulation. To provide a more sensitive, hence a more accurately responsive, short-clrcuiting switch mechanism in a device of the character indicated, is an object of the present invention.

Another object of the present invention is to provide in a carbon-pile regulator, novel means for combining switch mechanism therewith, in such manner that both are subject to the same operating forces.

A further object is to provide novel operating means for a carbon-pile regulator.

These and other objects of the invention will become apparent from inspection of the following specification when read with reference to the accompanying drawing wherein is illustrated the preferred embodiment of the invention. It is to be expressly understood, however, that the drawing is for the purpose of illustration only, and is not designed as a definition of the limits of the invention, reference being had to the appended claims for this purpose.

In the drawing:

Fig. i is a longitudinal sectional view of a device embodying the invention;

Fig. 2 is a transverse view along line 2-2 of Fig. 1; and

Fig. 3 is a diagram of the electrical connections.

In Fig. 3 numeral 5 designates a generator having a shunt field 6 across the mains 1 and 8 of which is bridged a battery 9. Serially connected in the shunt field circuit is the variable resistance unit Ii in the form of a pile of carbon discs 26 stacked in a retaining capsule 23 (see Fig. 1) that is mounted in a metallic spool 13 provided with heat radiating (cooling) fins l6, separated one from the other by spacer rings i2. A nut l'l threadedly engages the threaded end i8 of the spool i 3, and serves to adjustably clamp the spacers l2 and fins i6 against the shoulder IQ of the spool; a second shoulder 21 facilitating staking of the spool to the supporting plate 22. The insulating capsule 23 is interposed between the spool i3 and the carbon stack 26, and current is fed to the carbon stack by Way of terminal plug 29 threaded into the hub 3| of the retainer ring 32. Plate 22 is insulated from ring 32, as shown at 34 and 35;

apertures 36 being provided to receive retaining screws or bolts (not shown). A solenoid is provided, and includes a magnetic core 4| fixed to a magnetic housing 42 (as indicated at 43), a winding 44 on said core, and an armature 48 movable with respect to the core 4!, to engage magnetic flange 41 of the housing 42 when the winding 44 is energized, and to be disengaged therefrom by the action of resilient members 5i when the winding 44 is de-energized. Members ii are secured to the armature assembly by screws 52, as indicated.

The novel means for transmitting the movement of solenoid armature 46 to the carbon stack 26 will now be described. A coupling element 8|, whose flange BI is secured to the armature assembly by screws 52, is slidably received within a second coupling element 63, and a dished washer" type of annular spring is interposed between flat surfaces on said coupling elements, as indicated at 64. Coupling element 63 is threaded into a yoke 66, and coupling element Si is counter-bored to receive a current conducting contact screw 68 and a sleeve 61 of insulating material. A second contact screw 69 is carried by a plate H which is in turn carried by yoke 68, and a second plate 14 is carried by said yoke and serves to connect the yoke to a swivel coupling element 13 whose co-operating element 76 has operative connection with the end portion i8 of spool II. A nut 8i allows adjustment of the gap between coupling elements 6| and 63, and hence controls the setting (initial stress) of spring 64.

From the foregoing it will be apparent that the position of the armature 46 with respect to the stationary magnetic elements 4| and 41 will depend upon the strength of the magnetic field built up by the current flowing through the winding A l, and thus in turn will depend upon the prevailing voltage across the mains I, 8 of the generator circuit. When the voltage tends to rise above the normal value, the magnetic field will be increased sumciently to draw the armature into actual abutment with the magnetic pieces ill and at (this being the position indicated in Fig. 1) and in this position the springs 55 are fully stressed and the pressure upon the carbon stack 2% is at the minimum due to the fact that the actuating assembly including the parts 63, 65, it and 13 are now in their extreme left-hand position, as viewed in Fig. 1, and therefore they apply a minimum of pressure to the carbon stacks. The result is that the resistance to current flow through the carbon elements is at a maximum and therefore the tendency is for the field current to be reduced in strength thereby tending to reduce the speed of the generatorand thus restore the voltage across the mains l, 8 to normal. As this restoration takes place the resultant decrease in voltage across the winding 44 and the consequent weak ening of the magneticfield permits the springs 58 to assert themselves, thus tending to shift the assembly including the parts 6| 64, 63, 66, i4 and 33 to the right-all these parts moving as a unit, and with no substantial relative movement as between the parts 6! and 63 during the initial stages of this rightward movement. when the resulting compression of the carbon stack proceeds sufliciently to present substantial resistance to further rightward movement of the assembly, the stress in the spring 64 builds up and finally there is a snap action of said member 6 at which time the springs 5! become effective to follow up the snap action of the spring 84 by a sharp rightward movement of the member 8|; and as the member lil thus moves to the right to shift its position in relation to the resisted However,

member 83, there is a positive closing of the circuit to the contacts 68 and B9 and the resulting short circuiting bf the carbon stack 26. This action eliminates any residual resistance remaining in the carbon stack and thus increases the current flow through the shunt field l6 sufiiciently to accelerate the generator to the extent necessary to maintain normal speed and voltag output. When the speed and output again rises above normal, the cycle is repeated and thus regulation is maintained.

What is claimed is:

1. In a regulator of the carbon pile type, for regulation of generator voltage, a pair of relatively movable switch members in shunt with the carbon pile, means for preventing relative movement of said switch members upon generator voltage fluctuations of relatively slight magnitude, said preventing means including an electromagnetic armature assembly responsive to voltage fluctuations, means positively connecting said armature assembly with one of said switch members, and lost-motion means connecting said armature assembly with the other of said switch members.

2. In a regulator of the carbon pile type, for regulation of generator voltage, a pair of relatively movable switch members in shunt with the carbon pile, means for preventing relative movement of said switch members upon generator voltage fluctuations of relatively slight magnitude, said preventing means including an electro magnetic armature assembly responsive to voltage fluctuations, means positively connecting said armature assembly with one of said switch members, and snap action means connecting saidarmature assembly with the other of said switch members.

- JOSEPH W. ALLEN. 

